<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <style>
    body{
      width: 100%;
      height: 100%;
      background: linear-gradient(#fb3 50%, #58a 50%);
      background-size: 100% 50px;
    }
    .main {
      width: 60%;
      height: 60%;
      position: fixed;
      top: 20%;
      left: 20%;
      background: linear-gradient(to right, #fb3 50%, #58a 50%);
      background-size: 30px 100%;
    }
    .xie{
      width: 60%;
      height: 60%;
      position: absolute;
      top: 20%;
      left: 20%;
      background: linear-gradient(45deg,
              #fb3 25%, #58a 0, #58a 50%,
              #fb3 0, #fb3 75%, #58a 0);
      background-size: 42.4px 42.4px;
    }
  </style>
</head>
<body>
  <div class="main">
    <div class="xie"></div>
  </div>
</body>
</html>
